Minimally invasive treatments using catheters to correct a serious cardiovascular problem has revolutionized cardiovascular care. Almost a million such procedures take place each year in the United States. These procedures are guided by X-ray visualization of the vessels, angiography. After several decades of research, it has been established that adding functional measurements, i.e. measures of blood pressure and flow, to guidance by angiography significantly improves patients' outcomes and reduces costs. However, most procedures today still use only angiography; currently, functional measurement requires expensive specialized devices and equipment and certain specialized skills. DVX has invented a new kind of blood flow measuring Doppler ultrasound sensor that is inexpensive and can be mounted directly on a catheter. In the Phase I proof-of-concept portion of the research program, this sensor, mounted on a dummy catheter, was shown to work well in animal trials. DVX also determined how a tiny chip pressure sensor could be mounted alongside of the flow sensor so that full functional measurement of blood pressure and flow could be accomplished by a device mounted on a catheter. Bench tests proved the device's high accuracy was not affected by the angle of the catheter to the blood flow, in contrast to previous Doppler ultrasound devices that suffered from orientation sensitivity. In the proposed Phase II, the pressure and flow sensors will be integrated onto procedural catheters, such as for balloon angioplasty or stent placement, and the safety and usefulness of the device in guiding procedures demonstrated in animal studies. It is the goal of Phase II to advance the development of the catheter-mounted device to where clinical trials on humans will be appropriate and desirable. These studies should lead to widespread application of functional measurement in catheter-based procedures, improving patient outcome and reducing costs for millions of patients per year.